//! # xrust::error
//!
//! XDM, XPath, XQuery and XSLT errors.

use core::{fmt, str};

/// Errors defined in XPath
#[derive(Clone)]
pub enum ErrorKind {
    StaticAbsent, /// XPST0001
    DynamicAbsent, /// XPDY0002
    StaticSyntax, /// XPST0003
    TypeError, /// XPTY0004
    StaticData, /// XPST0005
    StaticUndefined, /// XPST0008
    StaticNamespace, /// XPST0010
    StaticBadFunction, /// XPST0017
    MixedTypes, /// XPTY0018
    NotNodes, /// XPTY0019
    ContextNotNode, /// XPTY0020
    NotImplemented,
    Unknown,
}

impl ErrorKind {
    /// String representation of error
    pub fn to_string(&self) -> &'static str {
        match *self {
            ErrorKind::StaticAbsent => "a component of the static context is absent",
            ErrorKind::DynamicAbsent => "a component of the dynamic context is absent",
            ErrorKind::StaticSyntax => "syntax error",
            ErrorKind::TypeError => "type error",
            ErrorKind::StaticData => "wrong static type",
            ErrorKind::StaticUndefined => "undefined name",
            ErrorKind::StaticNamespace => "namespace axis not supported",
            ErrorKind::StaticBadFunction => "function call name and arity do not match",
            ErrorKind::MixedTypes => "result of path operator contains both nodes and non-nodes",
            ErrorKind::NotNodes => "path expression is not a sequence of nodes",
            ErrorKind::ContextNotNode => "context item is not a node for an axis step",
            ErrorKind::NotImplemented => "not implemented",
	    ErrorKind::Unknown => "unknown",
	}
    }
}

/// An error returned by an XPath, XQuery or XSLT function/method
#[derive(Clone)]
pub struct Error {
    pub kind: ErrorKind,
    pub message: String,
}

impl Error {
  pub fn to_string(&self) -> String {
    self.message.clone()
  }
}

impl fmt::Debug for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.write_str(&self.message)
    }
}

